Chemical constituents of Calophyllum brasiliense. 2. Structure of three new coumarins and cancer chemopreventive activity of 4-substituted coumarins.

Continuing our search for cancer chemopreventive agents from natural sources, we examined constituents of the stem bark of Calophyllum brasiliense. Three new 4-substituted coumarins named brasimarins A (2), B (3), and C (4) were isolated and characterized, along with 11 known coumarins belonging to the calanolides or inophyllums. We also discuss the inhibitory effects of these coumarins on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells.